Multichannel surface spark gaps

A study has been undertaken on high-pressure surface discharge switches potentially capable of moderate repetition rate operation. The parametric experiments reported were carried out utilizing the gaps as transfer switches, under pulse charging conditions, between several types of low-impedance transmission lines and a high-pressure rare-gas halide laser discharge, acting as the load. The effects of spark gap internal geometry, gas composition, and controlled changes in the laser load, upon gap multichanneling, closure simultaneity, and peak holdoff capability are discussed. These surface gaps, of length 66 cm, reliably close 19 channels per side (29 per meter) with a holdoff voltage greater than 120 kV and a closure simultaneity of ∼ 2 ns for the first 500 shots, increasing to ∼ 5 ns and remaining there for 10 000 shots, the test limit to date. Preliminary results at higher charging voltages have yielded intense multichanneling with holdoff voltages in excess of 210 kV.